Final answer:
Polychromatophilic cells in a Wright-Giemsa stained blood smear appear bluish, indicating young red blood cells. This staining technique allows for the differentiation of blood cell types and the identification of pathogens. Other stains like acid-fast are used to identify specific bacteria like M. tuberculosis.
Step-by-step explanation:
The term polychromatophilic refers to a cell that stains with more than one dye. In the context of a peripheral blood smear stained with Wright's-Giemsa stain, polychromatophilic cells typically appear bluish due to the mixture of eosin and methylene blue dyes. These cells are often young red blood cells, also known as reticulocytes. A blood smear that has undergone Wright's-Giemsa staining allows for the differentiation of various blood cells, including the identification of pathological cells, such as those infected with Anaplasma spp.. Besides red blood cells, the Wright-Giemsa stain will also stain the nucleus and cytoplasm of white blood cells in various shades of purple, assisting in the identification and counting of different types of white blood cells and detection of protozoal or bacterial pathogens.
Differential stains like Wright-Giemsa are crucial for visual inspection under a microscope to assess the appearance of blood cells and to perform blood cell counts. The process can also identify intracellular structures such as morulae in cells infected by certain pathogens. In contrast, other differential stains like the acid-fast stain are used for detecting specific bacteria such as Mycobacterium tuberculosis, which remains red or pink against a blue background after staining.